There are a variety of types of motorized wheelchairs which are known. These include three-wheel wheelchairs having a pair of rear wheels and a front wheel. With this arrangement, there are examples of both rear-wheel-drive and front-wheel-drive chairs. Alternatively, four-wheel motorized wheelchairs are also available. With this arrangement, the larger rear wheels are normally the driven wheels and the smaller front wheels are normally idler wheels. One major drawback of most three-wheeled and four-wheeled wheelchair arrangements is the fact that the motor and drive apparatus are permanently installed on the wheelchair. This results in high cost, excessive weight and a wheelchair which cannot be easily collapsed to be transported.
For these and other reasons, motorized attachments for standard wheelchairs have been developed. However, these attachments have suffered from the drawbacks of being overly complex and heavy so that the occupant or user of the wheelchair cannot easily connect and disconnect the motorized attachment to the wheelchair while in the chair.
For example, U.S. Pat. No. 5,016,720 issued to Coker, discloses a battery-powered steerable electric drive unit for detachable connection to a conventional wheelchair. The unit includes a clamp for receiving and being connected to a bolt extending from the frame underneath the wheelchair in a position inaccessible to the user.
U.S. Pat. No. 3,921,744 issued to Benoit et al. discloses a detachable drive means for a wheelchair that is manipulable by the occupant but is heavy and complex. The connecting means includes ramps that guide laterally-sliding pins toward their sockets and rotatable cams received in vertical slots at the forward ends of the wheelchair arm rests.
U.S. Pat. No. 4,503,925 issued to Palmer et al. discloses a steerable motorized power unit constructed for detachable coupling to a wheelchair. Coupling pins are provided with mounting plates which can be fixably clamped to the chair frame to engage with a downwardly opening recess formed in a member of the detachable power unit. However, this arrangement is also heavy and cumbersome.
In order to address these and other problems and to achieve an improved method and apparatus for attaching a motorized wheel to a wheelchair, the following invention has been developed.